A ventricular assist device (“VAD”) is a device which is used to assist the heart of a mammalian subject such as a human patient. A typical VAD includes a pump which is implanted in the body of the subject. The pump typically has an inlet connected to a source of blood to be circulated, and an outlet connected to an artery. Most typically, the inlet of the pump is connected to the interior of the left ventricle and the outlet of the pump is connected to the aorta, so that the pump operates in parallel with the left ventricle to impel blood into the aorta. The pump may be a miniature rotary impeller pump having an impeller disposed in a pump housing and driven in rotation by a small electric motor which may be closely integrated with the pump. The motor in turn typically is powered by an implantable power source such as a storage battery with an arrangement for charging the battery from an external power source.
VADs can be used to assist the heart of subjects suffering from conditions which impair the pumping ability of the heart. Such assistance can be provided permanently, or while the subject awaits a suitable heart transplant. In other cases, the assistance provided by the VAD allows the heart to heal.
Aortic valve biomechanics in patients with VAD support may be altered. This can be due to continuous ventricular unloading and may affect aortic valve opening behavior during VAD support. These altered biomechanics may be associated with aortic insufficiency, stenosis, commissural fusion, and thrombus formation during VAD support. Long-term VAD support can increase the incidence of some of these complications. Adjusting the pump speed to allow periodic opening of the aortic valve may prevent the altered aortic valve biomechanics, including leaflet fusion, stasis in the aortic root, and formation of thrombus in the aorta. A previous approach to aiding aortic valve opening has been limited to operating VADs at minimal pump speeds. This previous approach minimizes perfusion and is a one-size-fits-all solution that does not account for specific patient requirements. Thus improvements are desirable.